1. Field of the Invention
The present invention is relative to a method, used in a step of processing for ashing a photoresist resin film of a semiconductor wafer. The invention more particularly relates to a method for the removal of a photoresist resin film by ashing after carrying out photolithography, etching or ion implantation in a production process for a semiconductor device, such as LSI, VLSI and the like.
2. Description of the Prior Art
When the silicon wafer is carried to a processing device by means of a chamber or the like in a step of processing or measuring the silicon wafer, particularly the wafer is required to be posited and ranked in sequence on the basis of the asher defined as a flat formed under the silicon wafer. Nowadays, ashing by active oxygen plasma is carried out for ashing a photoresist resin film of a semiconductor wafer. A light/ozone asher includes a process chamber having a sample stage for supporting a sample processed with active oxygen generated by irradiating ozone with UV rays while not irradiating the sample with UV rays. In this ashing method, a photoresist resin film is oxidized by plasma-activated oxygen, decomposed and, in this way, removed from the semiconductor wafer.
For this reason, the asher is a machine for photoresist-removing in the semiconductor process. Normally whether accomplishment of the ashing process will be depended on the decision from Etch-Module-Asher Endpoint being accommodated variations, or just by the asher's running time. However, any sort of asher's running time is totally different to different each other process. Normally it will waste time and costing by the method of running time because of its difficulty in controlling and its taking a long time in controlling.
As well known, Etch-Module-Asher Endpoint will show the final decision of ashing process. The asher also will produce higher throughput by useful Etch Module Asher Endpoint mode. However, how to achieve accommodated variations of Etch-Module-Asher Endpoint or which accommodated variations of Etch-Module-Asher Endpoint being the better result will indeed concerned. Especially exact Dead-Time is the most important parameter to the ashing process. If the Dead-Time is too long or too short, the bad result will be unfortunately obtained.
From previous experiences, some sorts of disadvantages are obviously discovered the following:
1. The change of adjacent in Processing-Time is just only one, not changed again for the same Processing-Time. PA0 2. Silicon wafer should be firstly pre-coated an outer photoresist layer, therefore it will waste too much pieces of wafer and too much photoresist. PA0 3. It is necessary to abject Etch-Module-Asher Endpoint mode for other different Etch Module Asher Endpoint when changing different layer or substrate.
Inevitably, there is created order ranking in positing the wafer on the basis of the asher because of inertial of the silicon wafer and its unfeasible to accurately positing the wafer. In the conventional positing method, the stopping time is not predetermined and hence it is unfavourably impossible to arbitrarily posit the silicon wafer.